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What is knockout size?

Author

James Craig

Updated on February 28, 2026

What is knockout size?

A knockout for 1/2" conduit is 7/8", but the outside diameter of a 1/2" EMT fitting is about 3/4". 3/4" knockout is 1-3/32" (close enough to 1-1/8), and O.D. of 3/4" fitting is roughly 1".

Similarly, what is knockout trade size?

A knockout for 1/2" conduit is 7/8", but the outside diameter of a 1/2" EMT fitting is about 3/4". 3/4" knockout is 1-3/32" (close enough to 1-1/8), and O.D. of 3/4" fitting is roughly 1".

One may also ask, what size hole saw do I need for 2 inch EMT? For 2 1/2″ conduit, drill using a 3″ hole saw or 2 1/2″ conduit knockout punch (2.914″ or 74mm). For 3″ conduit, drill using a 3 5/8″ hole saw or 3″ conduit knockout punch (3.539″ or 89.9mm).

Subsequently, one may also ask, what is the outside diameter of 3 inch EMT?

ACTUAL OUTER DIAMETER

THIN WALL INCH SIZE (E.M.T.)ACTUAL OUTSIDE DIAMETER
2 1/2"=2.875"
3"=3.500"
3 1/2"=4.000"
4"=4.500"

Is electrical conduit measured by ID or OD?

The ID and ODThere will also be a maximum OD. This is a fixed number that can not be deviated from. For instance, a 1-inch rigid conduit will have an ID of 1.063 inch nominal while a 1 inch intermediate metallic conduit will have an ID of 1.12 inch nominal, yet both have the same knockout size of 1.375 inches.

What size is a 3/4 knockout?

3/4" knockout is 1-3/32" (close enough to 1-1/8), and O.D. of 3/4" fitting is roughly 1".

What trade size means?

Trade size is the term used to denote common vernacular in the industry. i.e. Instead of saying the dimension you just say Trade size 1 meaning 1" conduit. It is intended as a way to use common language when writing.

What size is a 1/2 knockout?

A knockout for 1/2" conduit is 7/8", but the outside diameter of a 1/2" EMT fitting is about 3/4". 3/4" knockout is 1-3/32" (close enough to 1-1/8), and O.D. of 3/4" fitting is roughly 1".

What size hole saws do electricians use?

“The primary sizes of hole saws used by electricians are in the 2- to 7-inch range depending on applications,” Brinson said. “Larger sizes usually are for installing recessed can lights, and sizes like the 2-inch saws are used for feeders.

What is the largest size of EMT conduit?

EMT Weights and Dimensions
Trade Size DesignatorNominal Outside Diameter
3783.500
3 1/2914.000
41034.500

What is the outside diameter of 4 inch EMT?

ACTUAL OUTER DIAMETER
THIN WALL INCH SIZE (E.M.T.)ACTUAL OUTSIDE DIAMETER
2 1/2"=2.875"
3"=3.500"
3 1/2"=4.000"
4"=4.500"

What is the OD of 1 inch EMT?

Outside Diameter of Conduit
SizeEMTRigid
1/2"0.7060.84
3/4"0.9221.05
1"1.1631.315

What does a 3 EMT weigh?

EMT Weights and Dimensions
Trade Size DesignatorNominal Wt. per 100 Ft. (30.5m)
253148
2 1/263216
378263

What is conduit size?

6 minutes | 10 Sep 2019. Conduit fill, also known as raceway fill, is the amount of a conduit's cross-sectional area occupied, or filled, by a cable or multiple cables. The fill is based on the cable outside diameter (O.D.) and the conduit inside diameter (I.D.).

What is the outside diameter of 3/4 EMT conduit?

Outside Diameter of Conduit
SizeEMTRigid
1/2"0.7060.84
3/4"0.9221.05
1"1.1631.315

How many conduits are in a bundle?

The lengths are used with galvanised circular boxes, which can be screwed on, if the lengths are cut then a new thread can be formed with a conduit stock and die set and the lengths can be bent with a Hilmor conduit bender. Each length is 3.75m long and are sold in bundles of either 8 or 4 depending on the diameter.

How is EMT measured?

Tubing is measured by the OUTSIDE DIAMETER (O.D.), specified in inches (e.g., 1.250) or fraction of an inch (eg. 1-1/4″). Pipe is usually measured by NOMINAL PIPE SIZE (NPS).

What size does electrical conduit come in?

In most home construction jobs, conduit sizes of ¾-inch to 1½-inch are the most common sizes of conduits that are used. For most residential construction jobs, these sizes are adequate for protecting wiring that runs throughout the home from the main breaker box to lights, outlets, and switches.

What size do hole saws come in?

What hole saw sizes are available? Hole saws come in a wide range of sizes, typically between 14mm – 210mm (½inch – 8 ¼ inches) in diameter. Some models of hole saw will have their measurements printed on the wall of the cutting blade.

What is the ID of 1 EMT?

EMT Weights and Dimensions
Trade Size DesignatorNominal Outside Diameter
1/21617.9
3/42123.4
12729.5

Is nominal pipe size OD or ID?

Nominal pipe size refers to only the outside diameter (OD) of a pipe making it somewhat vague. For example, when we say pipe size is 2 NPS, it refers to all the pipes having 2.375-inch (or 60.3 mm) as outside diameter irrespective of wall thickness and thus the inside diameter.

Is PVC measured in ID or OD?

PVC Pipe is identified by the ID (Inside Diameter) and is referred to as a "nominal" size which means "in name only." However this confuses people and most novices try to use the OD (Outer Diameter) to order parts. If you do this, measure the OD of your pipe and find it the 2nd column of the chart below.

What is the ID of 3/4 EMT?

EMT Weights and Dimensions
Trade Size DesignatorNominal Outside Diameter
U.S.Metricin.
1/2160.706
3/4210.922

What are standard pipe sizes?

The most common standard diameters are as follow: 0.5 inch (15 mm), 0.75 inch (20 mm), 1 inch (25 mm), 1.5 inch (40 mm), 2 inch (50 mm), 3 inch (80 mm), 4 inch (100 mm), 6 inch (150 mm), 8 inch (200 mm), 10 inch (250 mm), 12 inch (300 mm), 14 inch (350 mm), 16 inch (400 mm), 18 inch (450 mm), 20 inch (500 mm), 22 inch

How do you calculate ID from OD and wall thickness?

How to Calculate Wall Size Based on OD and ID
  1. Subtract the inside diameter from the outside diameter of the pipe. The result is the combined thickness of the pipe walls on both sides of the pipe.
  2. Divide the total pipe wall thickness by two. The result is the size, or thickness, of one pipe wall.
  3. Check for errors by reversing the calculations.

What is the ID of 1/2 EMT?

EMT Weights and Dimensions
Trade Size DesignatorNominal Outside Diameter
1/21617.9
3/42123.4
12729.5

What is the OD of 10 inch pipe?

Pipe Size Chart
PIPE SCHEDULES WALL THICKNESS (Inches)
NominalO.D. Inches80s & E.H.
1010.750.500
1111.750.500
1212.750.500

How do I measure pipe size?

Measure the Outside Diameter (OD) of your pipe or pipe fitting:
  1. Wrap a string around the pipe.
  2. Mark the point where the string touches together.
  3. Use a ruler or measuring tape to find the length between the tip of the string and the mark you made (circumference)
  4. Divide the circumference by 3.14159.

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